As described in PTL 1, for example, a coated cutting tool is known. In this cutting tool, (a) a composite nitride layer of Al and Ti having an average layer thickness of 0.5 μm to 5 μm as a lower layer, (b) a composite nitride layer of Al and Cr having an average layer thickness of 0.5 μm to 5 μm as an intermediate layer, and (c) a composite nitride layer of Al and Ti having an average layer thickness of 0.2 μm to 0.6 μm as an upper layer are formed to coat on a surface of a cutting tool body made of a tungsten carbide-based cemented carbide. This coated cutting tool is known to exhibit excellent fracture resistance and wear resistance in, for example, the high-speed heavy cutting of mild steel, stainless steel, or the like.
In addition, a coated rotating tool described in PTL 2 is proposed. PTL 2 discloses a coated rotating tool, such as a coated end mill, in which an end cutting edge is provided on a tool front end face, a peripheral cutting edge is provided on a tool peripheral face, and a hard coating layer is formed on the surface of the cutting tool body. In this coated rotating tool, a plurality of microparticles projects on the surface of the coating layer, the area ratio of microparticles projecting on a rake face is 2 area % to 10 area %, and the area ratio of microparticles projecting on a flank face is 10 area % to 30 area %. Furthermore, the average projection angle of the microparticles projecting on the rake face to the direction perpendicular to an interface between the cutting tool body and the coating layer is 5° to 20° (in a direction away from a cutting edge). It is known that this coated rotating tool improves the fracture resistance and wear resistance of the coated cutting tool.
In addition, a surface-coated cutting tool described in PTL 3 is proposed. In this coated cutting tool, a honed face is formed at an intersecting ridge portion between a rake face and a flank face on a surface of the cutting tool body. This surface of the cutting tool body is coated with a hard coating layer formed using a CVD method. In the surface-coated cutting tool, the rake face and the surface of the hard coating layer of the honed face are ground, and finely hollowed portions are present on the rake face than on the honed face. It is known that this coated cutting tool enhances the lubricity of the cutting tool to a work, and improves the fracture resistance and wear resistance of the cutting tool.
In addition, a coated cutting tool described in PTL 4 is proposed. In the coated cutting tool of PTL 4, a hard coating layer is formed using a PVD method. The layer thickness of an uppermost layer of the hard coating layer is 0.1 μm to 1.5 μm, and approximately 0.1 μm to 10.0 μm-wide pores are formed on the surface of the uppermost layer. It is known that, according to the coated cutting tool, the wettability of the surface of the hard coating layer is improved, and the frictional resistance is reduced.